packaging: Fix service conf location

In downstream, PACKAGE_NAME is 'rhevm-reports'. Always place conf in
/etc/ovirt-engine-reports/ovirt-engine-reports.conf.d.

Bug-Url: https://bugzilla.redhat.com/1149446
Change-Id: I4fecb6102c3ca9a1499d53a189694986c36e4115
Signed-off-by: Yedidyah Bar David <didi@redhat.com>